Implant and delivery system for neural stimulator

ABSTRACT

Apparatus is described, the apparatus including an oral surgical guide. The oral surgical guide includes an arch portion configured to be placed on a dental arch of a subject; and an extension portion extending from the arch portion, and shaped to define a guide hole. Other applications are also described.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims priority from Israel Patent ApplicationNo. 229345 to Dayan et al., entitled “Implant and delivery system forneural stimulator,” filed Nov. 10, 2013, which is incorporated herein byreference.

FIELD OF THE APPLICATION

Some applications of the invention relate generally to medicalprocedures and implantable devices. More specifically, some applicationsof the invention relate to the use of electrical devices forimplantation in the head.

BACKGROUND

Surgical guides are typically generated based on computed tomography(CT) image data, and provide a dentist with guidance as to an optimallocation for drilling into a jaw bone of a subject during implantationof dental implants.

U.S. Pat. No. 7,120,489 to Shalev and Gross, which is assigned to theassignee of the present patent application and is incorporated herein byreference, describes apparatus for modifying a property of a brain of apatient, including electrodes applied to a sphenopalatine ganglion (SPG)or a neural tract originating in or leading to the SPG. A control unitdrives the electrodes to apply a current capable of inducing (a) anincrease in permeability of a blood-brain barrier (BBB) of the patient,(b) a change in cerebral blood flow of the patient, and/or (c) aninhibition of parasympathetic activity of the SPG.

U.S. Pat. No. 7,117,033 to Shalev et al., describes a method fortreating a subject, comprising positioning at least one electrode atleast one site of the subject for less than about 3 hours, applying anelectrical current to the site of the subject, and configuring thecurrent to increase cerebral blood flow (CBF) of the subject, so as totreat a condition of the subject. The site is selected from the listconsisting of: a sphenopalatine ganglion (SPG) of the subject, a greaterpalatine nerve of the subject, a lesser palatine nerve of the subject, asphenopalatine nerve of the subject, a communicating branch between amaxillary nerve and an SPG of the subject, an otic ganglion of thesubject, an afferent fiber going into the otic ganglion of the subject,an efferent fiber going out of the otic ganglion of the subject, aninfraorbital nerve of the subject, a vidian nerve of the subject, agreater superficial petrosal nerve of the subject, and a lesser deeppetrosal nerve of the subject.

U.S. Pat. No. 7,561,919 to Shalev et al., describes apparatus forapplication to a subject, including an elongated support element havinga length of between 1.8 cm and 4 cm, and having proximal and distalends; and one or more electrodes fixed to the support element in avicinity of the distal end thereof, and adapted to apply an electricalcurrent to a sphenopalatine ganglion (SPG) of the subject. The apparatusfurther includes a receiver, fixed to the support element, andelectrically coupled to the electrodes; and a wireless transmitter,adapted to be placed in an oral cavity of the subject, and to bewirelessly coupled to the receiver. Other embodiments are alsodescribed.

SUMMARY OF APPLICATIONS

In some applications, a system is provided for delivery of a neuralstimulator implant for electrical stimulation of a sphenopalatineganglion (SPG) of a subject. Stimulation of the SPG typically treatsvarious acute brain hypoperfusion states, such as occur during acuteischemic stroke. Typically, the system includes apparatus comprising animplantable neural stimulator, a steerable delivery guide, and an oralsurgical guide.

The neural stimulator implant is configured to be passed through agreater palatine foramen of a palate of an oral cavity of a subject intoa greater palatine canal, such that the neural stimulator implant isbrought into a vicinity of a sphenopalatine ganglion (SPG), for example,into contact with the SPG. For some applications, the implant is aflexible implant configured to conform to the anatomical structure ofthe greater palatine canal, to facilitate advancement therethrough. Forsome applications, the implant comprises at least one electrode forstimulation of the SPG.

The neural stimulator implant is typically coupled to the steerabledelivery guide. For some applications, a distal end of the steerabledelivery guide is configured to puncture oral mucosa of the subject,allowing the neural stimulator implant to be passed through the palatein a minimally-invasive procedure, without requiring a prior surgicalincision in the mucosa. Typically, the distal end of the steerabledelivery guide is also configured to be passed through the greaterpalatine foramen into the greater palatine canal. The delivery guide issteered in the canal in order to deliver the neural stimulator implantto the SPG.

Typically, the surgical guide is generated based on CT data obtained byimaging the subject. Based on the CT data, the surgical guide is formedto provide a guide hole for locating the entrance to the greaterpalatine canal, such that the implantable neural stimulator may bepassed through the guide hole and then into the greater palatine canal.In particular, the surgical guide is typically configured for placementon the subject's dental arch, such that an extension portion of thesurgical guide extending away from the dental arch contacts the roof ofthe oral cavity of the subject, and the guide hole is therebyautomatically placed over the entrance to the greater palatine foramenof the subject.

For some applications, the surgical guide is generated based on datafrom both a CT scan and an intra-oral scan. For such applications, anintra-oral scan of the upper palate, teeth, and/or gums of the subjectis performed in addition to the CT scan, and the data from both scansare registered for preparation of the surgical guide. Alternatively, thesurgical guide is initially generated based on data from an intra-oralscan only, and subsequently CT data are used for preparing the guidehole in the surgical guide.

Thus, in accordance with some applications of the present invention, thesurgical guide is configured to guide an operating physician to thelocation of the greater palatine foramen of the subject, to facilitateadvancement of the neural stimulator implant therethrough by injectingthe implant into the canal. Additionally, the guide hole in the surgicalguide facilitates penetration of the mucosa at an appropriate angle forentrance into the greater palatine foramen at an angle suitable foradvancement of the neural stimulator implant through the canal. Furtheradditionally, the CT data in combination with the surgical guideprovides the operating physician with information regarding theanatomical structure of the greater palatine canal, thereby facilitatingnavigation and advancement of the implantable neural stimulator coupledto the steerable delivery guide through the canal. Thus, in accordancewith some applications, the surgical guide in combination with the CTdata, guides the passing through oral mucosa of the subject andnavigation of the neural stimulator implant within a complex anatomicalstructure. Additionally, but not necessarily, the surgical guideprovides guidance for drilling at a predetermined depth into the jawbone.

The surgical guide typically allows for use of the neural stimulatorimplant by facilitating precise and safe implant deployment at the SPG,even by a less-skilled surgeon. Similarly, in general, the surgicalguide allows a less-skilled surgeon to access the SPG in a safe andprecise manner (even in the absence of implanting a neural stimulatorimplant).

For some applications, the delivery guide is configured to facilitatedelivery of the neural stimulator to the SPG site without the need forthe physician to consider a navigation map of the greater palatinecanal. For some such applications, CT data regarding the anatomicalstructure of the greater palatine canal is used to create (typically by3D printing) a curved guide groove surface on a portion of the deliveryguide. When the neural stimulator is mounted on a distal end of thedelivery guide, it is advanced distally in the canal by advancement of aslide-bar of the delivery guide. At the same time, a guiding pin whichis disposed within the curved guide groove is advanced within thegroove, causing rotation of the slide-bar with respect to the deliveryguide, thereby steering the neural stimulator in the greater palatinecanal.

There is therefore provided, in accordance with an application of thepresent invention, apparatus, including:

an oral surgical guide including:

-   -   an arch portion configured to be placed on a dental arch of a        subject; and    -   an extension portion extending from the arch portion, and shaped        to define a guide hole.

For some applications, the extension portion extends from the archportion in a superior and lingual direction with respect to the arch.

For some applications, the apparatus includes:

a steerable implantable neural stimulator configured to apply electricalstimulation to a sphenopalatine ganglion (SPG) of the subject,

the guide hole is configured to guide the stimulator through a greaterpalatine foramen of a palate of an oral cavity of the subject and into agreater palatine canal of the subject.

For some applications, the guide hole is configured to guide thestimulator through the greater palatine foramen at an angle that issuitable for entering the greater palatine canal.

For some applications, the surgical guide is generated by using CT scandata of the subject and intra-oral scan data of the subject, and theguide hole corresponds to a location of a greater palatine foramen ofthe subject.

For some applications, a portion of the surgical guide corresponding toa surface of gum tissue of the subject is shaped in a curved manner thatmatches curvature of the gum tissue.

For some applications, the surgical guide is generated by using CT scandata of the subject and not using intra-oral scan data of the subject,and the guide hole corresponds to a location of a greater palatineforamen of the subject.

For some applications, the implant is shaped to define proximal anddistal portions, and the distal portion of the implant is configured topuncture oral mucosa of the subject.

For some applications, the implant is shaped to define proximal anddistal portions, and the distal portion of the implant includes at leastone electrode configured to apply electrical stimulation to asphenopalatine ganglion (SPG) of the subject.

For some applications, the surgical guide is formed by athree-dimensional printing process.

For some applications, the surgical guide is shaped by shaping a pliablematerial on the dental arch of the subject.

For some applications, the pliable material includes a thermoplasticmaterial.

There is further provided, in accordance with an application of thepresent invention, a method including:

using an oral surgical guide generated using CT data to determine alocation of a greater palatine foramen of a palate of an oral cavity ofa subject;

inserting a steerable implantable neural stimulator into the greaterpalatine foramen of the subject, through a hole in the surgical guide;and

advancing the stimulator through a greater palatine canal of the subjectto a sphenopalatine ganglion (SPG) of the subject.

For some applications, using the oral surgical guide generated using CTdata further includes using the oral surgical guide to determine asuitable angle for entering of the greater palatine canal, and insertingthe stimulator into the greater palatine foramen includes inserting thestimulator at the suitable angle.

For some applications, the method includes creating an opening in mucosaof the subject using the stimulator, and inserting the stimulatorincludes stimulator through the opening.

For some applications, the method includes coupling a tool, in which thestimulator is disposed, to the hole in the surgical guide, and creatingthe opening includes creating the opening while the tool is coupled tothe hole in the surgical guide.

For some applications, inserting the stimulator includes inserting thestimulator using a tool, and the method further includes, following theadvancing of the stimulator, allowing the tool to be withdrawn from thegreater palatine canal without dislodging the stimulator by disengaginga locking element of the stimulator from the tool.

For some applications, the locking element is shaped as a ball, anddisengaging the locking element includes disengaging the ball-shapedlocking element from the tool.

There is further provided, in accordance with an application of thepresent invention, apparatus for use with a tool, the apparatusincluding:

an oral surgical guide including:

-   -   an arch portion configured to be placed on a dental arch of a        subject; and    -   an extension portion from the arch portion, and shaped to        define (a) a guide hole, and (b) a protruding portion including        a first coupling element configured to lockingly couple to the        tool.        For some applications, the protruding portion is shaped to        define a screw thread.

There is further provided, in accordance with an application of thepresent invention, a method including:

using a processor, receiving CT data of an oral cavity of a subjectacquired while (a) a surgical guide and (b) one or more markers, were inthe oral cavity;

using the processor, identifying a position of one or more markers on adrill with respect to respective sites on the surgical guidecorresponding to the markers in the oral cavity; and

using the processor and the identified position, guiding drilling of ahole in the surgical guide, by the drill, at a site on the surgicalguide corresponding to a greater palatine foramen of the subject.

For some applications, the one or more markers are on the surgicalguide, and receiving the CT data using the processor includes receivingthe CT data using the processor, the CT data having been acquired whilethe surgical guide having the one or more markers thereon was in theoral cavity.

For some applications, the one or more markers in the oral cavity areone or more teeth of the subject.

For some applications, the surgical guide includes a thermoplasticmaterial and guiding drilling of a hole in the surgical guide includesdrilling a hole in the thermoplastic material.

There is further provided, in accordance with an application of thepresent invention, a method, including:

providing a flexible, elongate implant having electrodes thereon and anunconstrained shape having a bend at least at a distal end portion ofthe implant;

subsequently, advancing the implant through a greater palatine canal ofa subject; and

utilizing the bend at the distal end portion of the implant tofacilitate steering of the implant during the advancing of the implant.

For some applications, the implant includes a nitinol portion whichprovides the bend, and providing the implant includes providing theimplant having the nitinol portion.

For some applications, the method includes, following the advancing ofthe implant, leaving the implant in the greater palatine canal of thesubject while the distal end portion of the implant is constrained andnot bent as it was prior to the advancing of the implant.

There is further provided, in accordance with an application of thepresent invention, apparatus, including:

a flexible, elongate implant, the implant having an unconstrained shapehaving a bend at least at a distal end portion of the implant, theimplant including:

-   -   two or more electrodes;    -   a flexible portion disposed at least between the two electrodes;        and    -   a receiving coil configured to receive energy for powering        driving of the electrodes.

There is further provided, in accordance with an application of thepresent invention, apparatus including:

an elongated implantable neural stimulator having proximal and distalsites and configured to apply electrical stimulation to a sphenopalatineganglion (SPG) of a subject; and

electronic circuitry having first and second portions and coupledrespectively to the proximal and distal sites of the implantable neuralstimulator, the electronic circuitry in the first portion being flexiblycoupled to the electronic circuitry in the second portion.

For some applications, the apparatus includes a flexible connectingelement coupled to the first and second portions of the electroniccircuitry.

There is further provided, in accordance with an application of thepresent invention, apparatus for delivery of an implantable neuralstimulator to a sphenopalatine ganglion (SPG) of a subject, including:

a tool having a distal portion coupled to the implantable neuralstimulator and a proximal portion; and

a slide-bar at the proximal portion of the tool, the slide-bar includinga distal portion and a proximal portion, the proximal portion of theslide-bar being coupled to the stimulator such that distal advancementof the proximal portion of the slide-bar produces distal advancement ofthe stimulator, the proximal and distal portions of the slide-bar eachincluding a respective magnetic element, the magnetic elements beingconfigured to couple the proximal and distal portions of the slide-barto each other unless a distally-directed force applied to the distalportion of the slide-bar exceeds a threshold.

There is yet further provided, in accordance with an application of thepresent invention, a method including:

using an oral surgical guide generated using scan data selected from thegroup consisting of: intra-oral scan data and CT scan data, to determinea location of a greater palatine foramen of a palate of an oral cavityof a subject;

inserting a steerable implantable neural stimulator into the greaterpalatine foramen of the subject, through a hole in the surgical guide;and

advancing the stimulator through a greater palatine canal of the subjectto a sphenopalatine ganglion (SPG) of the subject.

For some applications, using scan data selected from the groupconsisting of intra-oral scan data and CT scan data, includes using CTscan data and not intra-oral scan data.

For some applications, using scan data selected from the groupconsisting of intra-oral scan data and CT scan data, includes usingintra-oral scan data and not CT scan data.

For some applications, using scan data selected from the groupconsisting of intra-oral scan data and CT scan data, includes usingintra-oral scan data and CT scan data.

For some applications, using the oral surgical guide generated using thescan data includes using the oral surgical guide generated using the CTscan data, and using the oral surgical guide generated using the CT scandata further includes using the oral surgical guide to determine asuitable angle for entering of the greater palatine canal, and insertingthe stimulator into the greater palatine foramen includes inserting thestimulator at the suitable angle.

For some applications, the method includes creating an opening in mucosaof the subject using the stimulator, inserting the stimulator includesinserting the stimulator through the opening.

For some applications, the method includes coupling a tool, in which thestimulator is disposed, to the hole in the surgical guide, and creatingthe opening includes creating the opening while the tool is coupled tothe hole in the surgical guide.

For some applications, inserting the stimulator includes inserting thestimulator using a tool, and the method further includes, following theadvancing of the stimulator, allowing the tool to be withdrawn from thegreater palatine canal without dislodging the stimulator by disengaginga locking element of the stimulator from the tool.

For some applications, the locking element is shaped as a ball, anddisengaging the locking element includes disengaging the ball-shapedlocking element from the tool.

There is yet further provided, in accordance with an application of thepresent invention, a method including:

receiving CT scan data and intra-oral scan data of a subject; and

using the CT and intra-oral scan data, generating an oral surgical guideshaped to define a hole, the hole being placeable against a location ofa greater palatine foramen of the subject.

For some applications, generating the oral surgical guide includes:

generating the oral surgical guide without the hole, using theintra-oral scan data;

subsequently, performing the step of receiving the CT scan data; and

subsequently, generating the oral surgical guide with the hole bycreating the hole using the CT scan data.

There is yet further provided, in accordance with an application of thepresent invention, apparatus for delivery of an implant to an anatomicalsite of a subject, the apparatus including:

a delivery tool having a proximal portion, and having a distal portionthat is coupled to the implant;

a surface at the proximal portion, the surface shaped to define a curvedguide groove based on data obtained by imaging the anatomical site ofthe subject;

a slide-bar slidably coupled to the proximal portion; and

a guiding pin disposed within the curved guide groove and configuredsuch that distal advancement of the slide-bar with respect to theproximal portion produces (1) relative motion of the guiding pin withrespect to the curved guide groove, and (2) rotation of the slide-barwith respect to a longitudinal axis of the delivery tool.

For some applications, the surface shaped to define the curved guidegroove is a surface of the delivery tool, and the guiding pin is fixedlycoupled to the slide-bar.

For some applications, the surface shaped to define the curved guidegroove is a surface of the slide-bar, and the guiding pin is fixedlycoupled to the delivery tool.

There is still provided, in accordance with an application of thepresent invention, a system including:

a CT scanning device configured to image a subject;

an intra-oral scanning device configured to image the subject; and

a three-dimensional printing device configured to generate, based on theCT and intra-oral scanning of the subject, a surgical guide that isshaped to define a guide hole for locating a greater palatine foramen ofa palate of an oral cavity of the subject.

The present invention will be more fully understood from the followingdetailed description of embodiments thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a system for delivery of a neural stimulator implant forelectrical stimulation of a sphenopalatine ganglion (SPG) of a subject,in accordance with some applications of the present invention;

FIG. 2 is a schematic illustration of a delivery guide being advancedthrough a guide hole of an oral surgical guide, in accordance with someapplications of the present invention;

FIGS. 3A-C are schematic illustrations of the surgical guide shaped todefine a guide hole for locating the entrance to the greater palatinecanal, in accordance with some applications of the present invention;

FIGS. 4A-D are schematic illustrations of the system for delivery of aneural stimulator implant for electrical stimulation of a sphenopalatineganglion (SPG) of a subject, in accordance with some applications of thepresent invention;

FIG. 5 is a schematic illustration of the neural stimulator implant forelectrical stimulation of a sphenopalatine ganglion (SPG) of a subject,in accordance with some applications of the present invention;

FIG. 6 is a schematic illustration of a tool for facilitating deliveryof a neural stimulator implant for electrical stimulation of asphenopalatine ganglion (SPG) of a subject, in accordance with someapplications of the present invention;

FIG. 7 is a schematic illustration of a tool for facilitating deliveryof a neural stimulator implant for electrical stimulation of asphenopalatine ganglion (SPG) of a subject, in accordance with someapplications of the present invention;

FIG. 8 is a schematic illustration of a neural stimulator implantmounted onto a tool for facilitating delivery thereof for electricalstimulation of a sphenopalatine ganglion (SPG) of a subject, inaccordance with some applications of the present invention;

FIGS. 9A-B are schematic illustrations of the neural stimulator implant,in accordance with some applications of the present invention;

FIG. 10 is a schematic illustration of the neural stimulator implant, inaccordance with some applications of the present invention;

FIG. 11 is a schematic illustration of the neural stimulator implanthaving a bent distal end, in accordance with some applications of thepresent invention;

FIGS. 12A-C are schematic illustrations of a tool comprising a guidinggroove for facilitating delivery of a neural stimulator implant forelectrical stimulation of a sphenopalatine ganglion (SPG) of a subject,in accordance with some applications of the present invention; and

FIG. 13 is a block diagram showing steps for preparation of a surgicalguide, in accordance with some applications of the present invention.

DETAILED DESCRIPTION OF APPLICATIONS

Reference is made to FIG. 1, which is a schematic illustration of asystem 20 for delivery of a neural stimulator implant 32 for electricalstimulation of a sphenopalatine ganglion (SPG) of a subject, inaccordance with some applications of the present invention. Typically,system 20 includes implantable neural stimulator 32, steerable deliveryguide 34, and an oral surgical guide 40.

Typically, neural stimulator implant 32 is configured to be passedthrough a greater palatine foramen of the hard palate of the oral cavityof the subject, into a greater palatine canal, such that the neuralstimulator implant is brought into a vicinity of a sphenopalatineganglion (SPG). For some applications, the implant is an elongated,flexible implant having an unconstrained shape and configured to conformto the anatomical structure of the greater palatine canal, foradvancement therethrough. For some applications, the implant comprisesat least one electrode, e.g., a wire electrode, for stimulation of theSPG. Typically, implant 32 is shaped to define a curved or bent distalend, which facilitates steering of the implant during the advancing ofthe implant in the canal. (For the purposes of the specification andclaims of the present patent application, the terms “curved” or “bent”with respect to the distal end of the implant are to be understood asinterchangeable.) Typically, following the advancing of the implant anddeployment thereof in the vicinity of the SPG, for some subjects, thedistal end of the implant is constrained and substantially not curveddue to the anatomy of the canal, which is generally straight in thevicinity of the SPG in these subjects. For other subjects, the canal iscurved in the vicinity of the SPG, and thus the distal end of theimplant is curved at its implantation site in the vicinity of the SPG.

For some applications, neural stimulator implant 32 is coupled tosteerable delivery guide 34. Implant 32 is configured to be passedthrough guide 34, such that both implant 32 and guide 34 are advancedthrough the greater palatine foramen into the greater palatine canal,and implant 32 is brought into a vicinity of a sphenopalatine ganglion(SPG). Steerable delivery guide 34 is retracted after placement ofimplant 32.

FIG. 1 shows an exploded view of neural stimulator implant 32 passedthrough delivery guide 34. Delivery guide 34 is typically less flexiblethan neural stimulator implant 32, and thereby facilitates smoothpassage of the implant through the greater palatine canal and properdelivery of implant 32 to the SPG.

For some applications, a distal end 33 of steerable delivery guide 34 isconfigured to puncture oral mucosa of the subject, allowing neuralstimulator implant 32 to be passed through the palate in aminimally-invasive procedure, without requiring a prior surgicalincision in the mucosa. Typically, the distal end of the steerabledelivery guide is also configured to be passed through the greaterpalatine foramen into the greater palatine canal. The delivery guide issteered in the canal in order to deliver the neural stimulator implantto the SPG. For some applications, neural stimulator implant 32 isconfigured to puncture or otherwise create an opening in the oral mucosaof the subject. Following insertion of implant 32 into the mucosa, thesurgeon may optionally seal the puncture site by applying pressure tothe puncture site in order to facilitate self-healing of the hole, e.g.,by keeping a finger on the puncture site.

FIG. 1 additionally shows surgical guide 40 (represented by the dottedstructure) placed on teeth 2 of a dental arch 54 of the subject. (It isto be understood that for subjects without teeth, guide 40 is placed onthe gums.) Surgical guide 40 is generated based on CT data of thesubject and typically serves as a guide for locating the entrance to thegreater palatine canal through the greater palatine foramen of the hardpalate. Surgical guide 40 comprises an arch portion 59 configured forplacement on dental arch 54, and an extension portion 58 (shown in FIGS.2-3) that extends away from the arch portion. The extension portion isshaped to define a guide hole 6 (shown in FIGS. 2-3), which provides anoperating physician with the location and preferred entry angle to thegreater palatine foramen. Typically the location and angle of theentrance to the canal, as well as the length of the canal, varies amongthe population. Therefore, surgical guide 40 allows safe and accurateentry into the canal, and navigation therethrough, in accordance withthe subject's anatomy, based on the CT data. Surgical guide 40additionally inhibits excessive insertion of implant 32 into the canal.

For some applications, a distal end 38 of an angular guide 36 is placedon extension portion 58 of surgical guide 40 to facilitate advancementof delivery guide 34 through guide hole 6 in surgical guide 40.Typically, distal end 38 plugs into hole 6, such that angular guide 36facilitates advancement of delivery guide 34 into hole 6 at thepreferred angle, based on the CT data. When angular guide 36 is lockedproperly in place with respect to surgical guide 40, delivery guide 34is released by turning knob 63 in order to allow advancement of guide 34through guide hole 6. A tool 70 is configured to direct advancement ofguide 34 through guide hole 6 and subsequently through the greaterpalatine foramen into the greater palatine canal. Handle 60 of tool 70is steered and/or advanced, in order to direct motion of steerabledelivery guide 34.

Typically, the passage of implant 32 and delivery guide 34 into thegreater palatine canal is facilitated by image-guided surgicaltechniques, e.g., using optical fiducial markers 50, 51 and 52 on tool70 (and/or fiducial markers on guide 34). For some applications, animage-guided surgery processor utilizes location data derived frommarkers 50, 51 and 52, in combination with fiducial markers on thesubject (e.g., placed on the teeth, face or a head of the subject) inorder to register the pre-operative CT data with the current position ofthe tool and thereby facilitate steering and advancement of steerabledelivery guide 34 through the greater palatine canal. Alternatively oradditionally, the image-guided surgery processor utilizes location dataderived from markers 50, 51 and 52 in combination with registration dataobtained by (a) contacting a tool with a fiducial marker to multiplespots on the subject's head that can also be identified in thepre-operative CT image, and/or (b) visualizing markers 50, 51, and/or 52when angular guide 36 is locked in place, for example, by pluggingdistal end 38 into guide hole 6 or by a locking mechanism (as describedherein below with reference to FIGS. 4A-C). For some applications,handle 60 comprises a linear and/or an angular encoder configured tofacilitate recording of location data indicative of the current positionand orientation of neural stimulator implant 32. It is noted that thefiducial markers described herein can be used both in order to identifylocations in the subject's anatomy, and also as a reference marker, inorder to continually allow the image-guided surgery processor toidentify a current position of the subject's head, which can move.

Additionally, slide-bar 57 on tool 70 facilitates advancement ofdelivery guide 34 distally through guide hole 6. Typically, slide-bar 57provides steering functionality for facilitating advancement of guide 34into the greater palatine canal. Bar 57 is typically slidable withrespect to handle 60. Advancement of slide-bar 57 with respect to handle60 advances delivery guide 34 through the greater palatine canal.Additionally or alternatively, marker 50 comprises steeringfunctionality and is rotated around a center thereof in order to steerguide 34 and neural stimulator implant 32 within the canal in order todeliver the neural stimulator implant to the SPG. Further additionallyor alternatively, handle 60 is rotated as indicated by arrow 13, inorder to advance and orientate steerable delivery guide 34 within thegreater palatine canal.

For some applications, additional steering options are employed to allowcontrol of the advancement of implant 32 within the canal. For example,using a joystick allows steering the implant in a left/right and up/downdirection, as well as rotation around an axis.

Typically, the greater palatine canal is curved and multiple openingsare naturally formed along the greater palatine canal. Therefore, propersteering of guide 34 within the canal generally ensures delivery ofguide 34 and neural stimulator implant 32 to the SPG.

For some applications, surgical guide 40 is coupled to or used inassociation with a second arch portion (not shown). The second archportion is typically configured for placement on a lower dental arch ofthe subject. The second arch portion typically stabilizes upper archportion 59, by pressing portion 59 against the upper teeth and palate.Additionally or alternatively, a stabilizing element 90 is placedbetween the lower and upper dental arches of the subject, andfacilitates the squeezing of arch portion 59 against the upper teeth andpalate.

Reference is made to FIG. 2, which is a schematic illustration ofsteerable delivery guide 34 being steered and advanced through guidehole 6 of surgical guide 40, in accordance with some applications of thepresent invention. Surgical guide 40 comprises arch portion 59configured for placement on dental arch 54 and extension portion 58which is shaped to define guide hole 6. Extension portion 58 contactsthe roof of the oral cavity of the subject, and guide hole 6 is therebyautomatically placed over the entrance to the greater palatine foramenof the subject.

Thus, in accordance with some applications of the present invention,surgical guide 40 is configured to guide an operating physician to thelocation of the greater palatine foramen of the subject, to facilitateadvancement of guide 34 therethrough. Additionally, guide hole 6 in thesurgical guide facilitates penetration of the mucosa at an appropriateangle for entrance into the greater palatine foramen at an anglesuitable for advancement of guide 34 through the canal. Furtheradditionally, the CT data in combination with the surgical guide providethe operating physician with information regarding the anatomicalstructure of the greater palatine canal, thereby facilitating navigationand advancement of implantable neural stimulator 32 coupled to steerabledelivery guide 34 through the canal.

FIGS. 3A-B are schematic illustrations of surgical guide 40 comprisingarch portion 59 configured for placement on teeth 2 of a subject, or ongums of the subject, in accordance with some applications of the presentinvention. Extension portion 58 extends, lingually and in a superiordirection, away from arch portion 59 and is placed in contact with theroof of the oral cavity of the subject. Extension portion 58 is shapedto define guide hole 6, which is automatically placed over the entranceto the greater palatine foramen when surgical guide 40 is placed onteeth 2, or gums, of the subject. For some applications, an adhesive,e.g., glue, is used to secure guide 40 to the teeth or gums of thesubject.

Typically the location of the greater palatine foramen varies among thepopulation. For example, in some subjects the greater palatine foramenis associated with the upper third molar tooth. In other subjects, thegreater palatine foramen is associated with the second molar or betweenthe second and third molar. It is noted that the location of guide hole6 is shown in the figures by way of illustration and not limitation. Itis understood that the location of guide hole 6 is set based on thelocation of the greater palatine foramen of each particular subject.Surgical guide 40 is typically custom-made based on a CT scan of thesubject, such that guide hole 6 is placed over the greater palatineforamen of each individual subject, in order to guide the physician tothe correct location.

Reference is now made to FIG. 3C. For some applications, surgical guide40 comprises a second extension portion 58 located contralateral toextension portion 58, for bilateral electrical stimulation of the rightand left SPG (e.g., for treatment of vascular dementia).

For some applications, surgical guide 40 is fabricated bythree-dimensional (3D) printing.

Alternatively, surgical guide 40 is manufactured by molding a pliablematerial, such as a thermoplastic sheet, and drilling guide hole 6 witha drill. (After the molding, a suitable process is used to make thepliable material generally rigid, e.g., by heat treatment or ultravioletcuring.)

Typically, the drill has markers (e.g., RF coils, or optical markers) inorder to ensure drilling of guide hole 6 in a proper locationcorresponding to the greater palatine foramen. Typically, prior todrilling of the hole, the unfinished surgical guide is placed on teethor gums of the subject and CT data of the oral cavity is acquired.Subsequently, the surgical guide is removed from the subject's mouth.Using a processor, the CT data of the oral cavity with the surgicalguide is received and is used to determine a desired position of thedrill. Directional and orientational guidance for performing thedrilling is generated using the one or more markers on the drill.Subsequently, the processor guides drilling of the hole in the surgicalguide at a site on the surgical guide which corresponds to the greaterpalatine foramen of the subject.

Reference is made to FIGS. 4A-C, which are schematic illustrations ofdental arch 59, comprising a locking mechanism 94, in accordance withsome applications of the present invention. Locking mechanism 94 isconfigured to lock tool 70 and angular guide 36 in place with respect tosurgical guide 40, such that delivery guide 34 and implant 32 areadvanced accurately through guide hole 6. Generally, locking mechanism94 comprises (a) a projecting portion of surgical guide 40 which istypically shaped to provide a screw thread on an outer surface ofprojection 72, and (b) a screw thread on an inner surface of the lockingportion on tool 70. The screw threads on projection 72 and on tool 70engage each other, thereby locking the projection to the tool.

FIG. 4A shows surgical guide 40 comprising arch portion 59 and extensionportion 58. For some applications, extension portion 58 furthercomprises projection 72, which protrudes away from extension portion 58.Projection 72 is typically shaped to define the screw thread profiledescribed hereinabove, on an outer surface of the protrusion (as shown).(Alternatively, the screw-thread is on the inner surface of theprojection.)

Reference is made to FIG. 4B. For some applications, angular guide 36,which is mounted to tool 70, comprises locking portion 46 which isshaped to define a screw thread (described hereinabove), configured toengage projection 72 on surgical guide 40. Locking portion 46 istypically rotated in order to lock locking portion 46 to projection 72,thereby restricting motion of delivery guide 34.

FIG. 4C shows locking mechanism 94 in a locked state thereof. It is tobe noted that surgical guide 40 is shaped to define a screw-shapedprojection 72 by way of illustration and not limitation. In general,surgical guide 40 may comprise a first coupling, and guide 36 and/ortool 70 may comprise a second coupling. The first coupling may comprisea male coupling while the second coupling may comprise a femalecoupling, or vice versa.

It is noted that locking mechanism 94 is described by way ofillustration and not limitation. For some applications, tool 70 andangular guide 36 are locked in place with respect to surgical guide 40by plugging distal end 38 into guide hole 6. For example, locking oftool 70 with respect to surgical guide 40 is allowed when angular guide36 is plugged into guide hole 6 at an appropriate angle and/or aparticular orientation (e.g., via a fin extending at 12 o'clock thatfits into a corresponding slot on surgical guide 40).

Reference is made to FIG. 5, which is a schematic illustration of anexample of neural stimulator implant 32 for electrical stimulation of asphenopalatine ganglion (SPG) of the subject, in accordance with someapplications of the present invention.

Neural stimulator implant 32 is typically 0.5-1.5 mm in diameter, e.g.,1 mm. Thus, advancement of implant 32 typically does not requiredilation of the greater palatine canal. Alternatively, placement ofimplant 32 includes pre-dilation of the greater palatine canal.

For some applications, neural stimulator implant 32 is electricallycoupled to circuitry 56 which is adapted to be placed outside thegreater palatine canal, e.g., the circuitry may be positionedsubmucosally in the oral cavity. For other applications, circuitry 56 isadapted for insertion into the oral mucosa of the subject. Followinginsertion of electronic circuitry 56 into the mucosa, the surgeon mayseal the puncture site by applying pressure to the puncture site inorder to facilitate self-healing of the hole, e.g., by keeping a fingeron the puncture site. Typically, neural stimulator implant 32 itself isconfigured for puncturing the oral mucosa.

For some applications, electronic circuitry 56 is advanced along anexterior of delivery guide 34 (as shown), until circuitry 56 is insertedinto the mucosa.

As shown in FIG. 5, implant 32 typically comprises at least two steeringwires 101 configured to facilitate steering of implant 32 within thegreater palatine canal. Additionally, implant 32 comprises a stimulationwire 102 coupled to an electrode 106, for electrical stimulation of thesphenopalatine ganglion (SPG) of the subject, once implant 32 isdelivered to the vicinity of the SPG.

Typically, the delivery apparatus comprises a pusher 104 disposed withindelivery guide 34 (FIG. 1), which is configured to advance implant 32within the greater palatine canal, e.g., by pushing an inner surface ofelectrode 106.

Reference is made to FIG. 6, which is a schematic illustration of animplantation tool 700 for facilitating delivery of a neural stimulatorimplant 320 (described hereinbelow with reference to FIGS. 9A-B and 10)to a sphenopalatine ganglion (SPG) of a subject, for electricalstimulation of the SPG, in accordance with some applications of thepresent invention.

Tool 700 is typically used in combination with surgical guide 40(described herein with reference to FIGS. 3A-C) and directs advancementof the neural stimulator implant through guide hole 6 in surgical guide40 and subsequently through the greater palatine foramen into thegreater palatine canal.

Tool 700 typically comprises a handle 600 and a distal tip portion 720.In general, prior to use, the neural stimulator implant is mounted indistal tip portion 720. FIG. 6 shows the implant partially protrudingfrom tip portion 720, as it appears after it has been initially advancedinto the greater palatine canal. (For clarity of illustration, surgicalguide 40 and anatomy are not shown.) Overall, tool 700 facilitatesadvancement of the implant toward the sphenopalatine ganglion (SPG) of asubject.

Typically, distal tip portion 720 plugs into surgical guide 40 tofacilitate accurate advancement of neural stimulator implant 320 throughguide hole 6 in surgical guide 40. Handle 600 comprises a slide-bar 570,which is slidable with respect to handle 600. Slide-bar 570 is typicallylocked in place, until it is released by a release mechanism 730 (e.g.,by turning a knob on handle 600), in order to allow advancement of theneural stimulator implant through the guide hole and into the greaterpalatine canal.

An operating physician typically slides slide-bar 570 along handle 600in order to advance implant 320 out of tool 700 and distally throughguide hole 6. Additionally, slide-bar 570 provides steeringfunctionality for facilitating orientation of the implant in the greaterpalatine canal. Advancement of slide-bar 570 with respect to handle 600advances the implant through the canal.

For some applications, slide-bar 570 is rotated as indicated by arrow130, in order to orient implant 320 within the greater palatine canal.Typically, a distal-most portion of implant 320 is oriented at anon-zero angle with respect to a longitudinal axis of the implant, suchthat the implant may be steered in the palatine canal in an analogousfashion to that in which a steerable guidewire is steered in thevasculature of a subject.

For some applications, the passage of implant 320 into the greaterpalatine canal is facilitated by image-guided surgical techniques, e.g.,using optical fiducial markers 500, 510 and 520 on tool 700. Two or morecameras 16 are used to image markers 500, 510, and 520. An image-guidedsurgery processor 18 coupled to receive the image data from the camerasutilizes location data derived from markers 500, 510 and 520, incombination with fiducial markers on the subject (e.g., placed onsurgical guide 40, or the teeth, face or a head of the subject) toregister pre-operative CT data (showing bony structures in general andthe greater palatine canal in particular) with the current position ofthe tool and thereby facilitate steering and advancement of implant 320through the greater palatine canal.

Alternatively or additionally, the image-guided surgery processorutilizes location data derived from markers 500, 510 and 520 incombination with registration data obtained by (a) contacting a toolwith a fiducial marker to multiple spots on the subject's head that canalso be identified in the pre-operative CT image, and/or (b) visualizingmarkers 500, 510, and/or 520 when distal tip portion 720 is secured tosurgical guide 40.

For some applications (in addition to or instead of using markers 500,510, and 520), handle 600 comprises a linear and/or an angular encoderconfigured to facilitate recording of location data indicative of thecurrent position and orientation of neural stimulator implant 320.

Reference is made to FIG. 7, which is a schematic illustration ofimplantation tool 700, generally as described herein with reference toFIG. 6. For some applications, slide-bar 570 of handle 600 comprises adistal portion 65 and a proximal portion 64, which are held connected toeach other by first and second magnetic elements 85 and 84 coupled tothe proximal and distal portion of slide-bar 570 and magneticallycoupled to each other. Proximal portion 64 of slide-bar 570 is coupledto implant 320 such that distal advancement of proximal portion 64 ofthe slide-bar produces distal advancement of the implant. Typically, thephysician advances the slide-bar by gripping distal portion 65 andapplying a distally-directed force thereto, such that the magneticcoupling causes proximal portion 64 to advance distally, and therebycause distal advancement of implant 320. If the force applied to distalportion 65 of slide-bar 570 in a distal direction exceeds a threshold(e.g., due to advancement of the implant being impeded), this typicallybreaks the coupling between the first and second magnetic elements,thereby discontinuing advancement of implant 320 and alerting theoperating physician to an issue relating to the proper placement ofimplant 320.

Reference is made to FIG. 8, which is a schematic illustration of neuralstimulator implant 320 extending from distal portion 720 of tool 700, inaccordance with some applications of the present invention. (Othercomponents of tool 700 are labeled 721 in FIG. 8). For someapplications, tool 700 comprises at a distal portion thereof, astainless steel tube 780 configured to engage a locking element 350 ofimplant 320. An engaging element 781 is configured to engage lockingelement 350 of implant 320 (shown in FIG. 8 as a ball by way ofillustration and not limitation). Typically, activation of animplant-release mechanism 630 (e.g., by turning a knob as shown in FIG.6) causes engaging element 781 to disengage from locking element 350,allowing all implantation apparatus in the greater palatine canal to bewithdrawn, generally without dislodging implant 320 from itsimplantation location near the SPG.

Typically, tube 780 is shaped to define a series of slits 324longitudinally aligned along tool 700, each slit disposed at an angularoffset (e.g., a 180 degree offset as shown in FIG. 8, or alternativelyat a 90 degree offset, not shown) from an adjacent one of the slits. Theslits permit tube 780 to bend in a range of directions, e.g., in anydirection, to facilitate advancement of the implant through the greaterpalatine canal.

Implant 320 is generally flexible but typically also comprises a rigidportion 321 which houses a receiving coil 322 configured to receivepower from a remote power source to power implant 320.

Reference is now made to FIGS. 9A-11, which are different views ofimplant 320, in accordance with some applications of the presentinvention. As shown, implant 320 comprises proximal 352 and distal 354portions. Implant 320 is a generally flexible, elongate implant havingelectrodes (e.g. a dome electrode 12 and a second electrode 14) at thedistal portion thereof and an unconstrained shape that is curved, i.e.,bent, in a vicinity of the distal portion (e.g., proximal to electrode14, or between electrodes 12 and 14). FIGS. 9A-B and 10 show implant 320in a straight configuration. Typically, following the advancing of theimplant and deployment thereof in the vicinity of the SPG, distalportion 354 of the implant is constrained and shaped differently due tothe anatomy of the canal compared to its unconstrained shape. Forexample, distal portion 354 may be generally straight in the vicinity ofthe SPG, based on the anatomy of some subjects, or distal portion 354may be curved at its implantation site in the vicinity of the SPG.

Implant 320, in particular distal portion 354, is typically configuredto puncture oral mucosa of the subject in order to allow advancement ofimplant 320 into the greater palatine canal. For some applications,implant 320 is not configured to puncture the oral mucosa, but instead adistal portion of tool 700 is configured to puncture oral mucosa.

It is noted that for some applications, implant 320 comprises two ormore portions of electronic circuitry comprising multiple circuitryunits 326, at discrete longitudinal sites along implant 320 (shown inFIG. 10). Typically, the electronic circuitry is divided into first andsecond portions 17 and 19, which are coupled respectively to proximaland distal sites of implantable neural stimulator 320 that are flexiblycoupled to each other. Division of the electronic circuitry into two ormore portions typically facilitates smooth advancement of the implant inthe canal.

For some applications, a flexible, connecting element 328 (e.g., aflexible printed circuit board) extends along implant 320 and connectsfirst and second portions 17 and 19 of the electronic circuitry.Alternatively or additionally, a structural element 325 able towithstand compressive forces associated with the implantation is used toconvey distally-directed forces toward the distal end of implant 320.For example, this structural element may comprise nitinol (and for someapplications is not used to convey electrical signals between the firstand second portions of the electronic circuitry). Structural element 325comprising nitinol typically has a trained natural curve, which enablessteering of implant 320 by rotating the handle 600 of tool 700 (FIG. 6).The curve in element 325 could be as shown in FIG. 11, or between thetwo electrodes on distal portion 354, or within 15 mm of the very distaltip.

FIG. 11 shows neural stimulator implant 320 having a curved or bentdistal end, as described hereinabove, in accordance with someapplications of the present invention.

Reference is made to FIGS. 1-12C. For some applications, a surfaceshaped to define a guiding groove is generated (typically by a 3Dprinting process) based on CT data obtained by imaging the subject.Based on the CT data, the guiding groove is shaped in accordance withthe subject's anatomy in order to guide the implant to the desiredanatomical site, e.g., to guide steering of neural stimulator implants32 and/or 320 through the greater palatine canal to the vicinity of thesphenopalatine ganglion (SPG).

As shown in FIG. 12, a delivery tool, e.g., implantation tool 700,comprises a surface shaped to define a curved guide groove 920 at aproximal portion 710 of the delivery tool. Curved guide groove 920 isgenerated based on data obtained by imaging the anatomy of the subject,e.g., the greater palatine canal. A guiding pin 940 is typicallydisposed within curved guide groove 920, and is configured such thatadvancement of slide-bar 570 with respect to proximal portion 710produces (1) relative motion of guiding pin 940 with respect to curvedguide groove 920, and (2) rotation of slide-bar 570 with respect to alongitudinal axis of tool 700.

Typically, as the operating physician slides slide-bar 570 along handle600, guide groove 920 correctly guides the pin, thereby steering theimplant in the canal (i.e., by causing rotation of slide-bar 570 asindicated by arrow 130 in FIG. 6, at the correct point in thelongitudinal advancement of slide-bar 570 to cause a correspondingsteering of implants 32 and/or 320).

For some applications, guiding pin 940 is attached to implantation tool700, e.g., guiding pin 940 is fixedly coupled to slide-bar 570 of tool700. For such applications, the surface shaped to define curved guidegroove 920 is a surface of tool 700. For other applications, guiding pin940 is attached to tool 700 (e.g., to handle 600 and not to theslide-bar) and slide-bar 570 is shaped to define the surface with curvedguide groove 920.

It is noted that these applications using the guiding groove may, buttypically do not, utilize optical markers 500, 510, or 520, or manyother electronic surgical guidance techniques known in the art. For someapplications, the techniques described in this paragraph may be used foradvancement of other tools, in sites other than the greater palatinecanal (e.g., to facilitate endoscopic sinus surgery, or vascularcatheterizations).

Reference is made to FIGS. 3A-B and FIG. 13. For some applications,surgical guide 40 is generated based on data from both a CT scan and anintra-oral scan. For such applications, an intra-oral scan of the upperpalate of the subject is performed in addition to the CT scan, and thedata from both scans are registered for preparation of surgical guide40.

An intra-oral scan typically contributes to fabrication of abetter-fitting surgical guide 40 by providing high-resolution data ofthe upper palate including mapping of soft-tissue anatomy such as oralmucosa. For example, a portion of surgical guide 40 that corresponds toa surface of gum tissue of the subject is typically shaped in a curvedmanner that matches curvature of the gum tissue.

Thus, hole 6 is properly placed over the soft tissue that covers thegreater palatine foramen. Having the surgical guide fit better over theoral mucosa typically facilitates optimal puncturing and penetration ofthe greater palatine foramen.

As described hereinabove, data obtained from the CT scan regarding boneand hard tissue of the subject, are typically used to determine thelocation and angle of implant insertion as well as guiding advancementof the implant to the SPG. Combining the data from both the CT scan andthe intra-oral scan typically results in an enhanced surgical guide 40in which both bone structure and the shape of soft tissue of the oralcavity are both reflected in surgical guide 40.

FIG. 13 is a block diagram showing steps of obtaining both CT scan dataand intra-oral scan data for preparation of a surgical guide, inaccordance with some applications of the present invention. Typically,in step 80, a subject in need of electrical stimulation of the SPG isidentified. A CT scan and an intra-oral scan are then performed, asshown in steps 81 and 82. In step 83 the data from the CT and intra-oralscans are registered, and subsequently the surgical guide is planned andfabricated using the data from both the CT and intra-oral scanning(steps 86 and 87). As described hereinabove, surgical guide 40 istypically fabricated by three-dimensional printing techniques.

It is however noted that for some applications, surgical guide 40 isgenerated based on CT data only. Alternatively, for some applications,surgical guide 40 is generated based on intra-oral scan data only.

For some applications in which surgical guide 40 is generated based onintra-oral scan data only, a CT scan is performed after surgical guide40 is generated. For example, CT data of the subject may be acquiredwhile surgical guide 40 is disposed within the oral cavity, andregistration of surgical guide 40 with respect to hard tissue of theanatomy may be performed using one or more markers affixed to surgicalguide 40, and/or using features of the anatomy (e.g., teeth) that areimaged in the CT scan and in the intra-oral scan. The CT data typicallyguide the surgeon to drill a hole in surgical guide 40 at a site on thesurgical guide that corresponds to the greater palatine foramen of thesubject. For example, this drilling may be facilitated by markers on thedrill, as described hereinabove. Subsequently, to drilling the hole,surgical guide 40 may be placed in the mouth and used to facilitate aprocedure, as described hereinabove.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present inventionincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

The invention claimed is:
 1. A method comprising: using an oral surgicalguide generated using CT scan data and comprising (a) an arch portionconfigured to be placed on a dental arch of a subject, and (b) anextension portion extending from the arch portion, and shaped to definea guide hole to determine (i) a location of a greater palatine foramenof a palate of an oral cavity of the subject, and (ii) a suitable anglefor entering a greater palatine canal; inserting a steerable implantableneural stimulator at the suitable angle into the greater palatineforamen of the subject, through the hole in the surgical guide; andadvancing the stimulator through the greater palatine canal of thesubject to a sphenopalatine ganglion (SPG) of the subject.
 2. The methodaccording to claim 1, wherein the oral surgical guide is generated usingintra-oral scan data and the CT scan data.
 3. The method according toclaim 1, further comprising creating an opening in mucosa of the subjectusing the stimulator, wherein inserting the stimulator comprisesinserting the stimulator through the opening.
 4. The method according toclaim 3, further comprising coupling a tool, in which the stimulator isdisposed, to the hole in the surgical guide, and wherein creating theopening comprises creating the opening while the tool is coupled to thehole in the surgical guide.
 5. The method according to claim 1, whereininserting the stimulator comprises inserting the stimulator using atool, and wherein the method further comprises, following the advancingof the stimulator, allowing the tool to be withdrawn from the greaterpalatine canal without dislodging the stimulator by disengaging alocking element of the stimulator from the tool.
 6. The method accordingto claim 5, wherein the locking element is shaped as a ball, and whereindisengaging the locking element comprises disengaging the ball-shapedlocking element from the tool.
 7. A method comprising: using an oralsurgical guide generated using CT scan data to determine (i) a locationof a greater palatine foramen of a palate of an oral cavity of asubject, and (ii) a suitable angle for entering a greater palatinecanal; inserting a steerable implantable neural stimulator at thesuitable angle into the greater palatine foramen of the subject, througha hole in the surgical guide; and advancing the stimulator through thegreater palatine canal of the subject to a sphenopalatine ganglion (SPG)of the subject, wherein inserting the stimulator comprises inserting thestimulator using a tool, and wherein the method further comprises,following the advancing of the stimulator, allowing the tool to bewithdrawn from the greater palatine canal without dislodging thestimulator, by disengaging a locking element of the stimulator from thetool, and wherein the locking element is shaped as a ball, and whereindisengaging the locking element comprises disengaging the ball-shapedlocking element from the tool.